Pneumatically timed electric switch arrangement



A ril 13, 1965 R. A. FRISK 3,173,524

PNEUMATICALLY TIMED ELECTRIC SWITCH ARRANGEMENT Filed April 20, 1962 3 Shegts-Sheet 1 FIG;

INVENTOR, RALPH A. FRISK ATTORNEYS April 13, 1965 FRlsK 3,178,524

PNEUMAT I CALLY T IMED ELECTR I C SWI TCH ARRANGEMENT Filed April 20, 1 962 5 Sheets-Sheet 2 FIG. 3

INVENTOR.

RALPH A. FRISK ATTORNEYS April 13, 1965 R. A. FRISK 3,178,524

PNEUMATIGALLY TIMED ELECTRIC SWITCH ARRANGEMENT Filed April 20, 1962 3 Sheets-Sheet 3 FIGS FIG. 6

FIG? 50 5| 53 seasssf 65 k FIGS) up. I V 6e INVENTOR RALPH A.FR|SK VM,%W

ATTORNEYS United States Patent C) "ice 3,178,524 PNEUMATXCALLY TIMED ELECTREC SWITCH ARRANGEMENT Ralph A. Frislr, Rock Island, Ill., assignor, by mesne assignments, to E. W. Bliss Company, Canton, (lino, a

corporation of Delaware Filed Apr. 20, 1962, Ser. No. 189,674 11 Claims. (Cl. 266-34) The present invention relates generally to pneumatic timers and more particularly to a pneumatically timed or controlled device armed or set to one condition by movement in one direction, and by a timed return movement set to a second condition. Although certain broader features of the invention have application in other pneumatically timed devices such as valves with reciprocating members, a pneumatically timed electric switch is described hereinafter as an embodiment of the invention.

Pneumatic timers have been and are quite commonly used for actuating electrical switches. These timers comprise a chamber with a movable wall; an actuating plungor for moving the wall to a non-normal condition against a restoring force such as a return spring, thereby changing the volume of the chamber; check valve means for either admitting air to or exhausting air from the chamber relatively freely accordingly as the chamber volume is increased or decreased on arming by such plunger or Wall movement; means for venting or admitting air to the chamber, at a controlled and usually adjustable timed rate, according to the arming displacement of the wall as it is returned to an initial or normal condition by the restoring force; and means connecting the wall or plunger to the timed device.

In the case of a timed electric switch, an actuating member reciprocable plunger is in some manner connected with a movable element of the switch, so that as the timer is set or armed upon an initial plunger movement, by manual, solenoidal, hydraulic or pneumatic motor means or the like, the switch in thrown to one condition; and then, after timed return of the diaphragm and associated actuating member to a certain position, is then thrown to an opposite position or condition. Usually the time of delay or actuation is adjustable by setting of the air metering rate through a needle valve.

In striving for simplicity, low cost and reliability, consonant with the required load rating and performance in such timed devices, the prior art has developed pneumatic timers with elastic diaphragrns, usually of elastomeric material, clamped in sealed relation about its periphery to a chamber defining member. Commonly the check valve means includes a centrally apertured region of the diaphragm and cooperating movable valving elements. These elements are located on or associated with a centrally disposed actuating plunger usually extending through the diaphragm, at times being secured thereto or being slightly movable relative to the diaphragm.

The present invention proposes the use of a diaphragm secured only at spaced locations on its periphery there to form check valve means with cooperating casing members and avoiding perforation of the center of the diaphragm for any actuator or valving structure. A quite simple diaphragm may be used, readily stamped or die cut out of sheet stock. There is a decided advantage also by the fact that the central area which is particularly stressed by the actuating means is not weakened by perforations or the like. One casing member, in cooperation with which a timing air chamber is defined by the diaphragm as a flexible or movable wall, has a simply formed annular seat formation located entirely within and symmetrically relative to the points on the periphery at which the diaphragm is locally secured.

3,178,524 Patented Apr. 13, 1965 With this arrangement, when the diaphragm is displaced say inwardly, from normal position by an appropriately shaped actuating plunger, when the contained air escapes between the seat formation and the adjacent edge portions of the diaphragm between each two successive points of attachment which are free to move away from the seat. As soon as the plunger is released to initiate diaphragm return motion by a return spring, thereby decreasing the air pressure in the chamber, external air pressure moves the edge portions of the diaphragm into sealing relation with the seat in a flap type valve check valve type action, and the return of the diaphragm is as usual under the control of means admitting air to the chamber as a controlled rate.

Appropriate actuating plunger guide means as well as a particular form of plunger and return spring means are hereinafter disclosed which obviate need for passing the plunger or any other structure through the central portion of the diaphragm, and for any type of molded insert in the diaphragm.

It is the general object of the present invention to provide an improved diaphragm type pneumatic timer. Another object of the present invention is to provide a novel pneumatic timer structure wherein desired capacity, pertormance and reliability may be obtained at a lower cost.

Another object of the present invention is to provide quite simplified diaphragm structure and means of attaining required check valve function. Another object of the present invention is to provide a pneumatic timer of the general type described wherein the diaphragm cooperates with an adjacent timer casing member to provide the valving necessary for putting the controlled air chamber in communication with the external atmosphere for air passage as required at the time of arming the device. A still further object of the invention is to provide a timer of the type described having a diaphragm of relatively simple character produceable from sheet elastomeric stock, which requires no perforations or other interruption of the continuity of the diaphragm material in a central region acted upon by an actuating plunger and return spring.

Other objects and advantages of the present invention will appear from the followin description and the drawings wherein:

FIG. 1 is a generally vertical section through a pneumatically timed electric switch unit involving the present invention, taken substantially as indicated by the line 1-1 in FIG. 2;

FIG. 2 is a plan view of the lower part of the unit hous ing or casing with certain parts removed to show the structure of the switch housed therein;

FIG. 3 is a fragmentary detail of an actuating button and of an associated plunger element, viewed at from the position in FIG. 1;

FIG. 4 is a top plan view of the unit with certain parts broken away;

FIG. 5 is a fragmentary longitudinal vertical section of an adjustable valve for varying the flow of air;

FIG. 6 is a plan view of a diaphragm supporting plate;

FIG. 7 is a plan view of a plunger spring supporting plate;

FIG. 8 is a plan view of a diaphragm element;

FIG. 9 is a fragmentary view taken at 9-9 in FIG. 2; and

FIG. 10 is a fragmentary view corresponding to FIG. 5 of a modification in the air metering structure.

In the drawings, the present invention is shown as embodied in a pneumatic timer-electric switch unit adapted for operation manually, or by some powered means such as a solenoid or the like. The unit is shown as including a casing generally square in plan having a lower portion indicated by the general reference numeral It), preferably molded of insulating plastic providing a housing for a switch mechanism 11, an upper portion 12 also conveniently of molded plastic having a recessed or hollow interior defining a timing air chamber 14 with diaphragm 15 as a movable wall, and secured in cap-like fashion to the lower casing member by screws 16 threaded into corners of the lower casing.

Pneumatic T z'mei' Structure The pneumatic timer section proper, indicated by the general reference numeral 20, includes air metering means 21 (see FiG. a diaphragm or plunger return spring 22 with upper end received in a cylindrical central locating recess 24a in the hollow cover boss 24 and lower end acting on the central portion of the diaphragm through a disk-like spring pressure pad 25 having a round boss 25a inserted in the lower end of the spring.

A somewhat symmetrical diaphragm supporting ring plate 27 (see FIG. 6) with inner edge rounded at 27a, is loosely supported at the central portion of each of its short arms on a respective shoulder 28a provided on vertical rib formations 28 and block formations 32 integrally formed on the walls of the lower casing member. The shoulders 28:: are spaced downwardly from surface 31 by about the plate thickness, so that the plate top surface is at or slightly below the top surface 31. The plate 27 has near each corner air vent perforations 27b and inward corner notches 27c accommodating the vertical post-like integral corner formations 29 extending like the ribs from the bottom wall 39 upward to the plane of the continuous top surface 31 of the lower casing member.

Each corner of the symmetrical diaphragm 15 (FIG. 8) perforated at 15a is received preferably loosely over a diaphragm anchoring boss or annular projection 3.1 slightly higher than the thickness of the diaphragm material; and is also provided with a pair of smaller apertures 1511 located to be in alignment with underlying apertures 27b in the diaphragm supporting plate for purposes to be described. The diaphragm is formed of rubber-like elastomeric sheet stock, preferably silicone rubber.

Through a circumferential skirt or flange portion 35 top member 12 seats in dust-sealing relation upon the peripheral top surface 31 on the lower member; and has within the skirt portion 35 a downwardly facing annular band or seat formation 36 on the order of one thirtysecondth of an inch wide and spaced away from the top surface of the ring 2'7 to provide a diaphragm clearance on the order of five to ten thousandths of an inch. The cover securing bolts 16 are threaded downwardly into blind holes through the bosses 33 into the corner post thickening formations 29.

With this arrangement, when the diaphragm moves up as the timer is armed, air escapes through the clearance provided between the upper surface of the diaphragm and the ring seat 36 to pass downwardly into the lower chamber through the aligned diaphragm and plate apertures 15:) and 27b; and also around the edge or" the diaphragm, through clearance which may be provided between the diaphragm edge and the skirt 35 and such small gap as exists between the edge of the plate 27 and the inner surface of the casing 10.

An externally accessible cylindrical actuating button 40 (FIGS. 1 and 3) is received in the central bore of a bottom wall boss 30a aligned with the hollow boss 24, the counterbore at 3% affording a stop shoulder for button flange 4% to retain the actuating button in the casing. A plate member ll with a downward tang or extension 41a -received in a diametric button top slot 480 has oppositely disposed guide wings Mb, projecting beyond the counter bore with clearance relative to the bottom wall when 49 is in downmost position, loosely guided by short projections 32a of block formations 32.

An exhaust chamber diaphragm pressure pad 45 having a disk larger in diameter than and coaxial with pad 25, has a central coaxial stern 45b terminating in a button or enlargement tSc transversely slotted at 45d to fit over the upper end of plate 4 1. The entire pad assembly is reciprocably guided by a spring support plate 47 centrally apertured to accommodate the stem 45!; and supported at opposite ends and secured by screws 48 on the large shoulders 32b formed at a level lower than diaphragm plate supporting ribs 28a on thick ribs 32. A conical spring 49, with upper narrower end centered about the short cylindrical boss 45a of the pad 45, is interposed between the pad 45 and plate 47 to bias the pad upwardly into light engagement with the diaphragm.

The air needle valve or metering means vEll is housed in an integral molded somewhat T-shaped formation 56 on the top of cover member 12 with the leg of the T merging into the boss 24. (FIGS. 4 and 5.) The relatively large cylindrical bore 51 extending generally radially to and at its inner end through passage 52 and the boss recess 24a communicating with the air chamber, receives a needle valve body sleeve 53 sealed to the bore 51 and the surrounding cover structure by an O-ring 55 at its inner end to provide a tapered valve seat 56 cooperating with the end of a longitudinally adjustable needle valve member 57.

At either side of the bore 51, a respective chamber filled with a felt filter "ass 558 communicates through a respective radial sleeve aperture 53b with the space interior of the sleeve about the needle valve 57, and thereby through the seat 56, and the passage 52 with the air chamber 114. A cap member 60 secured by screws 61 on the vertical face of the formation 5% has filter chamber inlet ports tla, a central aperture 6312 through which extends the threaded outer end of needle member 57, and on its inner face a vertical slot 66c running upwardly from the bottom edge thereof. The width of the slot 60c is slightly greater than the width between hex faces of acorn type nut 62 held against rotation therein and having a tapering surface directed towards and sealed to the sl eve 53 by an O-ring 64. Preferably this is an elastic nut, that is, having within its metallic body not only a threaded portion engaged with the adjusting needle 57, but also an elastic rubberlike member sealing the nut to the threaded needle.

A modification of the structure of FIG. 5 appears in FIG. 10, similar parts having similar reference numerals. Under one aspect to simplify assembly of the overall structure, the equivalent of the cap 60 can as here be provided by an upward projection molded integrally with the lower casing and having an inwardly facing and endwise upwardly open slot 69c, a narrower slot 6th! for needle 57, and as well apertures for air inlet ports in portions covering the filter chambers. The broad end of the formation 50 would then be brought out to a corresponding position at the side of the cover memer, so that as the cover member is dropped into place with the needle and other elements of the metering arrangement 21 already in position, the nut 64 and needle 57 then enter the open ends of the slots ilc, 60d from above.

Also the inner end of bore 51 is provided with a tapered seat 56a; and sleeve 53 of FIG. 5 is replaced by needle guide sleeves 537, 53g between which is interposed spring 65. Sleeve 53 has a pair of parallel flats 66 milled across the right end exposing a counterbore from the left end to put air passage 63 in communication with the orifice at 56a despite journaliing support of the inner needle end in the narrow bore of 53 The sleeve 53g has a reduced diameter over its major length to enter and support spring 65, thrusting 53 against the end of bore 51. Where the direction of meter air flow is reversed as in a timer with air metered out of a chamber, the modification and the structure of FIG. 5 can of course omit filters in this region.

Switch structure The switch assembly 11 (FIGS. 1 and 2) here includes two pairs of fixed vertically spaced upper and lower contact elements 71, 72, generally L.-shaped and substantially right and left hand forms, with terminal portions projecting through corresponding slots of the side Wall of member 1%. The inner portion of the lower member is generally fiat and supported on the bottom wall that of the upper member 71 being supported on a shoulder 74a of an integral block formation located between an adjacent corner thickening formation 2? and rib 28; and the sides of the members 71, 72 being located by adjacent vertical portions of the formations 29.

As movable switch contact means there is provided an assembly including like opposed metal switch blades 75, 75 having bifurcated inner ends seated in respective groove formations 76 in opposite faces of the plate 41 for pivotally swinging their respective contact buttons 75a between the vertically aligned and opposed facing contact buttons 72a of corresponding pairs of vertically spaced fixed contact members. Slight shoulders at the outer ends of the grooves aid in locating the blades transversely. Aligned round bottom slots in the bottom end of the stem button 450 and top of plate 41 accommodate with clearance a switch helical tension spring '78, with ends hooked through the apertures 79 near the inner end of the blade bifurcating slots, for holding the plate inner ends seated in conductive engagement with the grooves 76.

The arrangement of the switch elements is such that when the button 44 is in its lowermost position the two plates are pivoted under the action of the spring upward beyond dead center, that is beyond a horizontal plane, i.e., perpendicular to plate 41, through the grooves '76 into contact with the upper contacts as shown in FIG. 1 thereby completing a circuit therebetween.

When the button is pushed inwardly displacing the seated ends of the blades with plate 41, free ends of the blades being restrained by contact with the upper contact elements, are relatively displaced downwardly against the bias of spring 78, (with blade contacts 75a sliding outwardly slightly on and rolling on contacts 71a) until past dead center where the plates are coplanar, whereupon the action of the spring then snaps them downwardly into contact with the lower contact buttons 72a, throwing the switch into its other position for the armed condition. Upon timed return of the system to normal condition under force of compressed spring 22, the reverse action occurs.

Upon inward motion of the button communicated through pad 45 to the diaphragm 15 against the return bias of spring 22 applied by pad 25, air escapes freely from the chamber 14 between the diaphragm and the seat 36, and the blades snap downward to contacts 7252. Upon lightening or release of the force applied to the button and incipient diaphragm return under the force of the spring 22, the diaphragm seals against the seat leaving the device armed or set for the time delayed actuation of the switch to normal condition as air is metered into the air chamber through the metering arrangement 21 at a rate primarily determined by the setting of the needle valve 57. The diaphragm is returned slowly downwardly and so also the movable switch member or elements until such time as dead center is passed at which point the plates quickly snap upwardly by toggle action of the arrangement into firm contact with the upper contact 71a.

The upper contacts 71 may be used as normally closed .contacts in a circuit which is interrupted by arming or setting the device and which is again closed after a timed period controlled by the metered flow of air into the upper chamber. Or conversely the lower contacts 72 may be used as normally open contacts in a circuit closed by arming and then reopened after the time delay established by the pneumatic timing section; or of course both sets of fixed contacts may be used for their respective functions.

I claim:

1. A pneumatically timed electric switch arrangement comp rising a first member having a central aperture at one end and providing a switch housing including a lower casing wall structure;

a cap member secured to the other end of the first member and having a downwardly facing recess; projections on the upper surface of the lower casing wall structure at peripherally spaced locations;

a diaphragm apertured to be anchored at its periphery,

on said projections and retained between said members, to define with the cap member recess an air chamber and forming a flexible chamber wall;

an annular seat formation on the inner face of the cap lying within the location of said projections;

means supporting the periphery of the diaphragm from below beneath said seat,

said diaphragm being supported with a normally slight clearance relative to said seat;

a return pressure pad bearing on but independent of the central top surface of said diaphragm and a centrally located diaphragm return spring interposed between the cap and said pad;

a centrally apertured guide plate supported by the lower casing in downwardly spaced relation from said support means;

an actuator pressure pad in a lower chamber bearing on but independent of the lower center surface of said diaphragm and having a stem extending through the aperture of said guide plate;

a compression spring interposed between the last said pressure pad and guide plate;

an actuating plunger reciprocably supported and guided in the said central aperture of the first member and having a stop formation cooperating with the lower Wall structure to retain the same therein;

connecting means for connecting said plunger to said stem, and reciprocating with the stem under axial forces applied externally to the plunger and by return action of said compression spring;

a switch including opposed fixed contact elements supported by the lower member,

oppositely extending switch blades having inner ends pivotally seated in parallel formations on the connecting means; and

a switch tension spring extending through a longitudinal slot in the connecting means and having opposite ends connected to respective blades,

said blades having inner ends slotted for accommodation of said spring;

and air flow control means controlling air flow through a passageway between the atmosphere and said air chamber.

2. A pneumatically timed electric switch arrangement asset forth in claim 1, said air flow control means comprising:

a housing provided by a bore extending inwardly from the exterior of said cap member and terminating in an end Wall having an aperture to said air cham her, and having an air port opening from the bore to the atmosphere;

a sleeve member in said bore biased toward the end wall and having an opening aligned with said aperture and communicating with said port providing a passageway between the atmosphere and said air chamber;

an elastic nut aligned with the outer end of said bore;

means sealing said nut to said housing;

means fixed relative to said housing and having a formation holding said nut captive and non-rotational;

and a needle valve member threaded through said nut ii in alignment with said aperture for controlling air fiow through said aperture.

3. A pneumatically timed electric switch arrangement as set forth in claim 2, wherein said sleeve has inner and outer ends resiliently sealed by interposed Q-rings to said end wall and said nut thereby to seal the nut to the housing.

4. A pneumatically timed electric switch arrangement as set forth in claim 2, including said sleeve and a flanged sleeve in the outer end of the bore and inward of said nut journalling axially spaced portions of said needle valve member,

and a pre-load compression spring interposed between said sleeves and about said valve member.

5. In a device having an air chamber, air flow control means comprising:

a housing providing by a bore extending inwardly from the exterior of said housing and terminating in an end wall having an aperture to said air chamber, and having an air port opening from the bore to the atmosphere;

a sleeve member in said bore biased toward the end wall and having an opening aligned with said aperture and communicating with said port providing a passageway between the atmosphere and said air chamber;

an elastic nut aligned with the outer end of said bore;

means sealing said nut to said housing;

means fixed relative to said housing and having a formation holding said nut captive and non-rotational;

and a needle valve member threaded through said nut in alignment with said aperture for controlling air flow through said aperture.

6. In a device as set forth in claim 5, wherein said sleeve has inner and outer ends resiliently sealed by interposed O-rings to said end wall and said nut thereby to seal the nut to the housing.

7. In a device as set forth in claim 5, including said sleeve and a flanged sleeve in the outer end of the bore and inward of said nut journalling axially spaced portions of said needle valve member,

and a pre-loaded compression spring interposed between said sleeves and about said Valve member.

8. A pneumatically timed electric switch comprising:

a first member having a central aperture at one end and providing a switch housing including a lower casing wall structure;

a cap member secured to the other end of the first member and having a downwardly facing recess; projections on the upper surface of the lower casing wall structure at peripherally spaced locations;

a diaphragm apertured to be anchored at its periphery,

on said projection and retained between said members, to define with the cap member recess an air chamber and forming a flexible chamber wall;

an annular seat formation on the inner face of the cap lying within the location of said projections;

means supporting the periphery of the diaphragm from below beneath said seat,

said diaphragm being supported with a normally slight clearance relative to said seat;

a return pressure pad bearing on but independent of the central top surface of said diaphragm and a centrally located diaphragm return spring interposed between the cap and said pad;

a centrally apertured guide plate supported by the lower casing in downwardly spaced relation from said support means;

an actuator pressure pad in a lower chamber bearing on but independent of the lower center surface of said diaphragm and having a stem extending through the aperture of said guide plate;

a compression spring interposed between the last said pressure pad and guide plate;

an actuating plunger reciprocably supported and guided if; in the said central aperture of the first member and having a stop formation cooperating with the lower wall structure to retain the same therein;

said plunger connected to said stem to move the stem under axial force applied externally to the plunger;

a switch supported by the lower member and actuated by axial motion of the stem;

and air fiow control means controlling air flow through a passageway between the atmosphere and said air chamber.

9. A pneumatic timer for a device actuated to opposite conditions by motion of an actuating element, comprising:

a first member having a central aperture at one end and providing a half housing;

a cap member secured to the other end of the first member and having a downwardly facing recess; projections on the upper surface of the first member wall structure at peripherally spaced locations;

a diaphragm apertured to be anchored at its periphery on said projections and retained between said members to define with the cap member recess an air chamber and forming a flexible chamber wall;

an annular seat formation on the inner face of the cap lying within the location of said projections;

the space about the external periphery of said seat communicating with the atmosphere;

means supporting the periphery of the diaphragm from below beneath said seat,

said diaphragm being supported with a normally slight clearance relative to said seat;

a return pressure pad bearing on but independent of the central top surface of said diaphragm and a centrally located diaphragm return spring interposed between the cap and said pad;

a centrally apertured guide plate supported by the first member in downwardly spaced relation from said support means;

an actuator pressure pad in a lower chamber bearing on but independent of the lower center surface of said diaphragm and having a stem extending through the aperture of said guide plate;

a compression spring interposed between the last said pressure pad and guide plate;

an actuating plunger reciprocably supported and guided in the said central aperture of the first member and having a stop formation cooperating with the lower wall structure to retain the same therein;

said plunger connected to said stem and moving the stem under axial force applied externally to the plunger;

means for moving said actuating element in response to motion of said stem;

and air flow control means controlling air flow through a passageway between the atmosphere and said air chamber.

10. A pneumatic timer for a device actuated to opposite conditions by motion of an actuating element, comprising:

a first member having a central aperture at one end and providing one part of a housing;

a cap member secured to the other end of the first member as a second part of the housing and having a downwardly facing recess;

projections on the upper surface of the first member wall structure at peripherally spaced locations;

a diaphragm anchored at spaced locations on its periphery and retained between said members to define with the cap member recess an air chamber and forming a flexible chamber Wall;

an annular seat formation in the inner face of the cap lying Within said location;

the space about the external periphery of said seat communicating with the atmosphere;

means supporting the periphery of said diaphragm with a normally slight clearance relative to said seat;

pressure pads bearing on opposite sides of but independent of the central region of said diaphragm and respective opposed bias means interposed between the housing and said pads;

a centrally apertured guide plate supported by the first member in spaced relation from said seat;

a stem on one pad extending through the aperture of said guide plate;

means for moving said actuating element in response to motion of said stem;

and air flow control meanscontrolling air flow through a passageway between the atmosphere and said air chamber.

11. A pneumatically timed electric switch comprising:

a first member having a central aperture at one end and providing a switch housing;

a cap member secured to the other end of the first member and having a recess facing the first member;

projections on the upper surface of the first member wall structure at peripherally spaced locations;

a flexible diaphragm apertured to be anchored between said members at spaced locations on its periphery and retained between said members to define with the cap member recess an air chamber and forming a flexible chamber wall;

an annular seat formation on the inner face of the cap lying within said locations;

said diaphragm being supported with a normally slight clearance relative to said seat and space about the exterior periphery of the seat communicating with the atmosphere;

a first pressure pad bearing on but independent of the central top surface of said diaphragm and a centrally located compression spring interposed between the cap and said pad;

a centrally apertured guide plate supported by the first member in downwardly spaced relation from said support means;

an actuator pressure pad in a lower chamber bearing on but independent of the lower center surface of said diaphragm and having a stern extending through the aperture of said guide plate;

a compression spring interposed between the second pressure pad and guide plate;

an actuating plunger reciprocably supported and guided in the said central aperture of the first member;

said plunger connected to said stem to move the stem under axial force applied externally to the plunger;

a switch supported by the lower member and actuated by axial motion of the stem;

and air flow control means controlling air flow through a passageway between the atmosphere and said air chamber.

References Cited in the file of this patent UNITED STATES PATENTS 2,790,597 Turpin Apr. 30, 1957 2,840,657 Roeser June 24, 1958 2,866,862 Bachi Dec. 30, 1958 3,040,842 Charbonneau June 26, 1962 

1. A PNEUMATICALLY TIMED ELECTRIC SWITCH ARRANGEMENT COMPRISING: A FIRST MEMBER HAVING A CENTRAL APERTURE AT ONE END AND PROVIDING A SWITCH HOUSING INCLUDING A LOWER CASING WALL STRUCTURE; A CAP MEMBER SECURED TO THE OTHER END OF THE FIRST MEMBER AND HAVING A DOWNWARDLY FACING RECESS; PROJECTIONS ON THE UPPER SURFACE OF THE LOWER CASING WALL STRUCTURE ON THE UPPER SURFACE OF THE LOWER CASING A DIAPHRAGM APERTURED TO BE ANCHORED AT ITS PERIPHERY, ON SAID PROJECTIONS AND RETAINED BETWEEN SAID MEMBERS, TO DEFINE WITH THE CAP MEMBER RECESS AN AIR CHAMBER AND FORMING A FLEXIBLE CHAMBER WALL; AN ANNULAR SEAT FORMATION ON THE INNER FACE OF THE CAP LYING WITHIN THE LOCATION OF SAID PROJECTIONS; MEANS SUPPORTING THE PERIPHERY OF THE DIAPHRAGM FROM BELOW BENEATH SAID SEAT, SAID DIAPHRAGM BEING SUPPORTED WITH A NORMALLY SLIGHT CLEARANCE RELATIVE TO SAID SEAT; A RETURN PRESSURE PAD BEARING ON BUT INDEPENDENT OF THE CENTRAL TOP SURFACE OF SAID DIAPHRAGM AND A CENTRALLY LOCATED DIAPHRAGM RETURN SPRING INTERPOSED BETWEEN THE CAP AND SAID PAD; A CENTRALLY APERTURED GUIDE PLATE SUPPORTED BY THE LOWER CASING IN DOWNWARDLY SPACED RELATION FROM SAID SUPPORT MEANS; AN ACTUATOR PRESSURE PAD IN A LOWER CHAMBER BEARING ON BUT INDEPENDENT OF THE LOWER CENTER SURFACE OF SAID DIAPHRAGM AND HAVING A STEM EXTENDING THROUGH THE APERTURE OF SAID GUIDE PLATE; A COMPRESSION SPRING INTERPOSED BETWEEN THE LAST SAID PRESSURE PAD AND GUIDE PLATE; AN ACTUATING PLUNGER RECIPROCABLY SUPPORTED AND GUIDED IN THE SAID CENTRAL APERTURE OF THE FIRST MEMBER AND HAVING A STOP FORMATION COOPERATING WITH THE LOWER WALL STRUCTURE TO RETAIN THE SAME THEREIN; CONNECTING MEANS FOR CONNECTING SAID PLUNGER TO SAID STEM, AND RECIPROCATING WITH THE STEM UNDER AXIAL FORCES APPLIED EXTERNALLY TO THE PLUNGER AND BY RETURN ACTION OF SAID COMPRESSION SPRING; A SWITCH INCLUDING OPPOSED FIXED CONTACT ELEMENTS SUPPORTED BY THE LOWER MEMBER, OPPOSITELY EXTENDING SWITCH BLADES HAVING INNER ENDS PIVOTALLY SEATED IN PARALLEL FORMATIONS ON THE CONNECTING MEANS; AND A SWITCH TENSION SPRING EXTENDING THROUGH A LONGITUDINAL SLOT IN THE CONNECTING MEANS AND HAVING OPPOSITE ENDS CONNECTED TO RESPECTIVE BLADES, SAID BLADES HAVING INNER ENDS SLOTTED FOR ACCOMMODATION OF SAID SPRING; AND AIR FLOW CONTROL MEANS CONTROLLING AIR FLOW THROUGH A PASSAGEWAY BETWEEN THE ATMOSPHER AND SAID AIR CHAMBER. 